An article of footwear for strengthening and relaxing foot and lower leg muscles

ABSTRACT

Footwear for strengthening and relaxing foot and calf muscles and for developing overall body coordination includes: a device for fastening the footwear to the user&#39;s foot, and a flat sole, the underside of which is in contact with the ground, and the upper side of which is provided with a training element for interacting with the user&#39;s foot, the training element being exchangeable, and fastenable in the upper layer of the sole. In another embodiment, the device for fastening the footwear to the foot includes elastic straps secured to the edges of the sole, and a flat sole, the underside of which contacts the ground, and the upper side of which is provided with a training element for interacting with the user&#39;s foot, the training element being an insole having through-slots through which the straps can be passed.

FIELD OF THE INVENTION

The present invention relates to an article of footwear designed for strengthening foot and lower leg muscles and developing overall body coordination, and to a kit for improving general physical fitness.

BACKGROUND

The human body, being an extremely complex system of ligaments, muscles, and tendons, with a sensitive upright vertebral column, has an active locomotive system and is naturally capable of moving over rough ground. For millenniums, people utilized and maintained their bodies in a manner determined by the conditions of such natural environment.

There is a large variety of exercises to assist in recovering from injuries, back pain treatment and prevention, lower limb blood circulation improvement and overall cardiovascular system strengthening, as well as in solving a wide range of medical and esthetic problems associated with excess weight or other issues. Foot deformities (either congenital, or acquired), various types of platypodia, as well as after-effects of injuries and neurological deficit, are mitigated, for example, by means of inserts into conventional shoes. It was believed that, as a result of continuous use of or wearing the inserts, correction would eventually occur. Unfortunately, the contrary was proven: when the tension is reduced, the muscular system becomes weaker as a result of it ceasing to perform its work function. Little or no allowance is made for either dynamic changes, or further development of the posture or locomotive system.

Orthotic insoles or inserts are commonly used to correct various foot problems and to treat certain foot disorders.

For example, a forefoot corrector known from Patent RU2341234 published 20 Dec. 2008, comprises an insole and an insert in the form of a plano-convex lens.

When buying footwear, people are usually guided by its appearance or comfort. Comfortable footwear is designed such as to ensure comfort for the wearer in walking or standing and often comprises suitable inner staffing, an arch support and comfortable insoles. In ordinary use, existing footwear provides a good stable base for the wearer's foot, thus requiring lower muscle strength for the wearer to maintain satisfactory equilibrium when standing still or walking.

Surprisingly, it was found out that, wearing footwear unstable to a minor, but still safe, degree, the wearer experiences more difficulties in maintaining equilibrium when walking or standing, thus having to apply more muscular activity to maintain good equilibrium equal to that provided by the use of existing footwear types. In particular, it has been found out that the muscles, such as tibialis anterius, tibialis posterior, rectus femoris muscles, m guadriceps femoris, m gluteus, have to work more when wearing footwear with minor instability. Furthermore, it is well known that human physiology is such that a muscle having to work more becomes stronger and recovers after loading in shorter time.

However, even with minor footwear instability, the habitual body equilibrium is lost, so walking in such footwear may not be considered completely safe and requires specific efforts and focus.

Our feet constantly support us, and, if such support is asymmetric or incorrect, everything above it goes imbalanced. Importance of the foot condition for the human health is so great, that any efforts aimed at improving overall health or building up other muscles of the body may fail to attain the desired effect in the presence of foot arch issues.

A foot itself has a complex structure: about 26 bones, 31 joints, and 20 muscles and ligaments belonging exclusively thereto. If foot ossicles which are to be stabilized by well-toned foot muscles are positioned incorrectly or displaced, the other muscles in the body fail to work even during normal walking, which will, at some point, also affect the internal organs. The spine and pelvis in their healthy condition provide for normal functioning of the internal organs.

The muscles and ligaments do not work as separate mechanisms; they are connected to each other. For example, foot flattening affects the entire leg and the spine. The thigh muscles have to be continuously tensioned to maintain the overloaded knee joint in an appropriate position. To stabilize the pelvis, the thigh flexor muscles get involved, in their turn pulling the lumbar spine. This causes excessive lumbar flexure and a number of pain feelings in feet, knees and thighs. That is why a muscular imbalance, for example, due to platypodia, cannot be corrected by just rolling a tennis ball with a foot.

Gymnastics and fitness training is the simplest and most effective way to maintain and improve one's general physical fitness: the cardiovascular system fitness, flexibility, muscular endurance, strength, power, developed sense of equilibrium, good motion coordination, reactions, agility, body fat-to-muscle ratio, as well as to maintain a healthy musculoligamentary system of the feet. Many exercises recommended for body conditioning include foot muscle training.

According to expert opinion, it also advantageous to diversify the basic training methods described in numerous sources: with every new variant, the body may be utilized in a different manner, while by changing the angle of motion, one can discover new possible ways of training.

Numerous exercises and foot training devices have been developed, yet, according to statistics, the vast majority of people with such issues only use orthotic insoles that neither assist in muscle strengthening, nor cause the foot to ‘work’, but rather provide a primarily compensatory effect, i.e. a ‘crutch’ for challenged feet. Other people live enduring pain or resort to operative treatment.

The reason is that exercises require self-discipline, daily expenditure of certain time, persistence, and patience, since it may take weeks or even months before the effect becomes noticeable, so many people quit exercising without achieving any effect. However, even if the effect is achieved, one should not quit training, as the muscular tonicity has to be continuously maintained. Experts emphasize that regularity is important for health maintenance. If at least some of the above recommendations become part of daily habits, one will be able to easily maintain his/her feet healthy even staying at home.

There is, therefore, a need for an article of footwear that will assist in strengthening the joints: foot joints, ankle joints, knee and hip joints, in toning and strengthening the muscles while the wearer is standing or walking as usual. At the same time, the article of footwear is to provide a balanced set of exercises aimed at groups of muscles and joints. Furthermore, the article of footwear is to be safe and stable with respect to a surface; walking in such article of footwear will not to be spontaneous, but rather predictable, for the body, and, as such, will not require more attention than usual. Furthermore, the wearer will not have to find special time for training sessions, as he/she will be able to train said muscles during routine activities, such as walking.

Various types of prior art footwear may be used for training; however, all such types of footwear are characterized primarily by their sole, specifically, by its surfaces that contact the soil or flooring and are of various shapes and configurations.

For example, Patent RU57086 published 10 Oct. 2006 discloses an article of footwear which may be used as a home training device to increase natural physical exertion and comprises a sole and a holder attached to the sole. The sole is designed to be positioned under the forefoot and is comprised of an upper portion and a lower portion secured together. The upper portion of the sole may be cylinder-shaped or parallelepiped-shaped, while the lower portion of the sole may be configured as a spherical segment or as a segment of a cylinder. In order to walk, the wearer of such article of footwear struggles to maintain equilibrium due to the lack of support on his/her heel and to an unstable swaying lateral position of his/her feet. When struggling to maintain equilibrium, the wearer's leg muscles, abdominal and gluteal muscles are contracting and his/her ligaments and joints become stronger. Said invention is disadvantageous in that walking in such footwear is somewhat of a challenge, during which all attention is to be focused on maintaining equilibrium, and the walking is unsafe. One may not, therefore, wear such article of footwear and engage in his/her domestic activities at the same time. It is also impossible to focus on training a specific group of muscles as necessary (for example, the ankle lateral and medial ligaments responsible for foot turning or the foot arch ligaments in case of platypodia).

Patent JP2007061563 published 15 Mar. 2007 discloses an article of footwear for improving and recovering foot muscle strength during sports activities. The article of footwear has a sole internally configured with a level variation of at least 15 mm in height along the portion from an interphalangeal joint to a metatarsophalangeal joint.

According to the claimed invention, a sole with a height variation is not arranged inside an article of footwear, but rather represents an open support for the foot. There is nothing to retain the toes in a bent position or to prevent them from freely moving up and down. The height variation is created to allow for free movement of the toes within a desired range, and it is through this movement that the foot toes and arch are trained. When stepping, the toes are reflexively searching for something to bear on, thus spontaneously pressing the sole surface.

Patent RU22465667 published 10 Feb. 2005 discloses an article of footwear for active rolling walk. An upper portion of the device is provided with a shoe top, and the sole comprises at least a sole middle portion, a sole lower portion and a sole bottom layer, wherein the lower layer of the sole middle portion and the sole bottom layer may have a convex shape, an arcuate shape or be in the form of a circular segment, as desired. The invention provides for joint protection, muscle building, and posture improvement.

When walking in such article of footwear, all attention is to be focused on maintaining equilibrium, and the walking is unsafe. One may not, therefore, wear such article of footwear and engage in his/her domestic activities at the same time.

The shoes or the walking devices as described above neither require the entire locomotive system to be utilized through active walking, nor require determining, on one's own and promptly, how the muscles, tendons and the vertebral column are to be utilized for active walking. Orthotic shoes or inserts may only be modified by an expert in orthopedics. The existing devices are, therefore, unsuitable for correcting minor and, possibly, temporary defects of posture and errors in the sequence of the locomotive system operation in a planned and prompt manner.

The prior art closest to the claimed solution is an article of footwear or a footwear insole known from International Publication WO2011059045 published 19 May 2011, by which flat-foot can be prevented or treated, weight can be reduced, and/or the plantar muscle can be trained or the leg muscle strength can be enhanced more efficiently. The footwear insole or the article of footwear has such a structure as to positively induce movements of wearer's digits of foot, in particular, open-close (clasp/unclasp) movements of the digits of foot. The footwear insole is provided, at the toe side of a body, with a raised ridge for placing the digits of foot thereon, on which the endphalanx of all of the digits of foot are placed when the wearer wears an article of footwear provided with the footwear insole therein and bends inward the distal interphalangeal joints, proximal interphalangeal joints and metacarpophalangeal joints of all of his/her first to fifth digits of foot.

The prior art articles of footwear, insoles and inserts for correcting defects or training are designed to act on a certain portion of a foot, i.e. for training only one group of muscles: the forepart, the portion under the toe bones or the portion under the heel; they do not allow for comprehensive training of multiple muscles and joints, i.e. such article of footwear (footwear insole) is not versatile enough to be used for various joints and groups of foot, leg, back, etc., muscles.

It is an object of the present invention to provide a comprehensive footwear technology allowing for combined training of various groups of muscles and joints. Furthermore, the technology has to be compact, i.e. should not take much space in a room or an entrance hall, should be lightweight and easy to use, safe and suitable for wearers of various ages, should be affordable for any wearer, and should allow training discreetly without interruption of routine activities. No complex devices are required in order to change the type of training; changing the type of training is done easily; moreover, by wearing the article of footwear, one may alternately engage the majority of the lower body joints and musculoligamentary system. The technology has to meet all the above requirements in order to perform a set of exercises.

DISCLOSURE OF THE INVENTION

The technical result is a wider range of technical means intended for home training, for improving general physical fitness and for strengthening foot and lower leg muscles as part of daily life. The claimed article of footwear is versatile, easy and safe to use even for elderly people; moreover, no considerable physical, economic or time expenditures are required to change the type of training.

The stated technical result is attained, in a first embodiment, by an article of footwear for strengthening foot and lower leg muscles and for developing overall body coordination, the article of footwear comprising a means for fastening the article of footwear to the wearer's foot, a flat sole, the underside of which is in contact with flooring, and the upper surface of which is constructed with a training element for interacting with the wearer's foot, said training element being designed to be exchangeable for changing the type of training and to be secured in the upper layer of the sole via a spike connection, snap fasteners, hook and loop fasteners, an adhesive layer, a textile fastener.

The article of footwear may be a slide shoe with a fastening means for fastening it on a foot in a variety of ways or a sandal (FIG. 1 a, 1 b, 1 c, 1 d, 1 e ). Preferably, the spike connection is a mortise and tenon (FIG. 2 a, 2 b ) or a tongue and groove (FIG. 4 ) connection.

Further, the sole may be made of an elastic polymer material, for example, rubber, PVC, polyurethane, ethylene vinyl acetate, polypropylene, polymer foam.

Furthermore, the article of footwear may be made without any distinctions in its shape (configuration), i.e. may be designed for wearing on either right or left foot.

The spike connection is configured in the form of tenons and respective mortises of different shapes arranged on the training element surfaces and the sole upper surface in contact with each other (ref to FIG. 2 a, 2 b ).

The spike connection is configured in the form of spikes and respective perforations arranged on the training element surfaces and the sole upper surface in contact with each other (ref to FIG. 3 a, 3 b ).

The training element may be configured in the form of a flat insole with a thickness of 5 to 60 mm (ref to FIG. 4 a, 4 b ).

The training element may be configured in the form of a semi-cylinder (ref to FIG. 5 a, 5 b ) or a polyhedron having its base secured on the sole upper surface along the longitudinal axis of the latter.

The training element may be configured in the form of an insole with a semi-cylinder or a polyhedron secured on its upper surface along the longitudinal axis (ref to FIG. 6 a , 66).

The training element is configured in the form of a flat insole having, on its upper surface, under the foot arch or under the waist area, a semi-cylinder or a polyhedron arranged perpendicularly to the longitudinal axis (ref to FIG. 7 ).

The training element may be configured in the form of a semi-cylinder or a polyhedron having its base secured on the sole upper surface, across the width of the sole under the foot arch or under the waist area, perpendicularly to the sole longitudinal axis.

The training element may be configured in the form of a sole segment having a triangular cross-section and narrowing towards the sole inner edge, which is arranged under the foot's outer side, thus causing the lateral border of the foot to be raised in the horizontal plane and causing the foot to be turned inwardly (ref to FIG. 8 ).

The training element may be configured in the form of a sole segment having a triangular cross-section and gradually narrowing towards the sole outer edge, thus causing the medial border of the foot to be raised in the horizontal plane and causing the foot to be turned outwardly (ref to FIG. 9 ).

The training element may be configured in the form of a sole forepart segment having a triangular cross-section and gradually narrowing towards the sole central part, thus causing the foot toe portion to be raised in the vertical plane (ref to FIG. 10, 11, 12 ).

The training element may be configured in the form of a sole forepart segment having a trapezoidal cross-section and gradually beveled towards the sole central part, thus causing the foot toe portion to be raised in the vertical plane.

The training element may be configured in the form of a flat insole having arranged, on its upper surface, in the forepart, a segment having a triangular cross-section and gradually narrowing towards the insole central part, thus causing the foot toe portion to be raised in the vertical plane (ref to FIG. 13 ).

The training element may be configured in the form of an insole having a triangular diagonal section and gradually narrowing in the direction from the outer heel seat region towards the inner forepart region, thus causing the outer region of the foot heel portion to be raised and causing the front inner region of the foot toe portion to gradually descend in the diagonal direction in the vertical plane (ref to FIG. 14 ).

The training element may be configured in the form of an insole having a triangular diagonal section and narrowing in the direction from the inner heel seat region towards the outer forepart region of the sole, thus causing the inner region of the foot heel portion to be raised and causing the front outer region of the foot toe portion to gradually descend in the diagonal direction in the vertical plane (ref to FIG. 15 ).

The training element may be configured in the form of an insole having a triangular diagonal section and narrowing in the direction from the outer region of the foot toe portion towards the inner region of the foot heel portion, thus causing the outer region of the foot toe portion to be raised and causing the inner region of the foot heel portion to gradually descend in the diagonal direction in the vertical plane (ref to FIG. 16 ).

The training element may be configured in the form of an insole having a triangular diagonal section and narrowing in the direction from the inner forepart region towards the outer heel seat region, thus causing the inner region of the foot toe portion to be raised in the vertical plane and causing the foot to be turned outwardly (ref to FIG. 17 ).

The training element may be configured in the form of a flat insole having its outer surface gradually sloping from the insole outer edge towards its inner edge, thus causing the foot outer portion to be raised in the horizontal plane and causing the foot to be turned inwardly (ref to FIG. 18 ).

The training element may be configured in the form of a flat insole having its outer surface gradually sloping from its inner edge to its outer edge, thus causing the foot inner portion to be raised in the horizontal plane and causing the foot to be turned outwardly (ref to FIG. 19 ).

The training element may be configured in the form of a part of a flat insole, which is arranged under the heel portion, arch and metatarsus and has a bench under the foot metatarsophalangeal joints (ref to FIG. 20 ).

The training element may be configured in the form of a convex hemisphere and arranged in the sole central part, wherein the surface in contact with the foot causes the foot's longitudinal arch to be flexed along the convex surface (ref to FIG. 21 ).

The training element may be configured in the form of a convex hemisphere arranged in the sole central part, wherein the surface in contact with the foot causes the foot's transverse arch to be flexed along the convex surface (ref to FIG. 22 ).

The training element may be configured in the form of an ellipsoid or a semi-cylinder and is arranged between the hallux and the second toe (ref to FIG. 23 a ).

The training element may be configured in the form of an insole having secured thereon, between the hallux and the second toe, an ellipsoid or a semi-cylinder (ref to FIG. 23 b ).

The training element may be configured in the form of an elastic insole having an upturned forepart region which straightens under the force exerted by the foot when walking (ref to FIG. 24 a, 24 b ). When walking, the toes press and release the forepart region, acting against the insole resistance.

The training element may further include an elastic tricot cover to provide a smooth surface for the foot to slide over, in the event the wearer is training without tricot socks (ref to FIG. 25 ). The tricot cover is secured onto the insole so as to provide for maximum sliding of the cover over a smooth surface. The training element having a smooth surface may be used without the tricot cover, wearing a conventional sock instead.

The training element may be configured in the form of an insole having an additional elastic porous layer on the outer surface, for example, of polyurethane foam, for example, as shown in FIG. 26 .

The additional elastic layer is used essentially to provide comfort and dampening when the foot is pressing any of the above hard training elements during a training session. It may be bonded with a conventional glue to a hard surface of a training element. The training element embodiments including the elastic porous layer are shown in FIGS. 27 a -j.

The elastic layer may cover only a portion of the hard surface of the training element, for example, only that under the toes, as shown in FIG. 27 j and FIG. 28 .

The stated technical result is achieved in a second embodiment of an article of footwear for strengthening foot and lower leg muscles and for developing overall body coordination, comprising a means for fastening the article of footwear to the foot, which is configured in the form of elastic slings secured at the edges of the sole, a flat sole, the underside of which is in contact with flooring, and the upper surface of which is constructed with a training element for interacting with the wearer's foot, the training element being configured in the form of an insole having through cutouts through which the slings can be passed.

The training element in this embodiment of the footwear article is configured in the form of an insole having holes to secure straps therein, as shown in FIG. 29 .

Alternatively, the training element is configured in the form of an insole having through cutouts at the insole edge to secure straps therein, as shown in FIG. 30 .

The stated technical result is achieved in a further embodiment of a training element configured in the form of a multi-layered insole comprised by successive layers of various densities: a flat bottom layer having its outer surface secured on the sole upper surface and having secured on its inner surface a hard element in the form of an ellipse or a semi-circle arranged under the foot arch, an intermediate layer formed of an elastic foam material and having a hole for the hard element, and a top flat layer, the outer surface of which is in contact with the foot, the layers being bonded to each other via a glue layer (FIG. 31 ).

The bottom layer is formed, for example, of ethylene vinyl acetate, the intermediate layer is formed of thermoplastic rubber, while the hard element and the top layer are formed of polypropylene. The central hard element is of elliptical or semi-circular section, as shown in FIGS. 31 a, 31 b, 31 c, 31 d , 31 e.

The central hard element supports the top hard layer which, due to the central element's rounded surface, bends, as shown, under the load from the foot tangentially in all directions, and acts as a pivot about which the foot can deflect to any direction within a small range determined by the insole thickness, thus ensuring both safe walking and calibrated instability requiring the lower limb and back muscles to be stabilized in order to maintain equilibrium, see FIGS. 31 f, 31 g , 31 h.

The stated technical result is achieved in a training kit comprising the article of footwear according the first or the second embodiment and at least two training elements configured to be exchangeable for changing the type of training.

For example, the training kit may consist of a set of the elements shown in FIG. 32 .

The article of footwear with training elements providing the following effects on a foot: a change in the foot position with respect to a flooring/ground surface (flexion angle, height); for example, pressure exerted to the foot (in a standing or walking position) from below by the training element via a dampening spring-elastic material, which pressure causes a response from the foot muscles; for example, displacement of the foot, when walking, with respect to a bearing surface, which is caused by a movably attached element with a small motion range within the insole/sole, etc.

Advantageously, the wearer of the article of footwear is urged to increase his/her muscle activity when standing or walking in order to maintain proper equilibrium. The muscles are, therefore, toned and strengthened when one is simply being in a standing position or is walking. In order to correct his/her equilibrium and to walk, the wearer is required to increase his/her muscle activity.

Where the instability is properly calibrated, it is barely perceptible for the wearer of the article of footwear. Yet, after having walked several steps or when wearing it to achieve physical fitness as part of normal way of life, the additional muscle activity so required may assist in strengthening and improving the physical fitness of groups of muscles, in particular, as part of an exercise or recovery regime. Most preferably, the article of footwear is to be used frequently and as part of a discreet regime of daily exercise and recovery.

DESCRIPTION OF THE FIGURES

FIG. 1 shows footwear models with various designs of the means for fastening to the foot.

FIG. 2 shows an article of footwear with a training element, wherein a connection is configured in the form of tenons and respective mortises.

FIG. 3 shows an article of footwear with a training element in the form of a semi-cylinder secured on the sole upper surface along the longitudinal axis of the latter via a tongue and groove connection.

FIG. 4 shows an article of footwear with a training element in the form of a flat insole following the shape of the sole of different thicknesses.

FIG. 5 shows an article of footwear with a training element in the form of an insole having a semi-cylinder along the longitudinal axis, which is secured on the sole outer surface via tongue and groove connections.

FIG. 6 shows an article of footwear with a training element in the form of an insole having a semi-cylinder along the longitudinal axis, which is secured on the sole outer surface by means of snap fasteners.

FIG. 7 shows an article of footwear with the training element in the form of a flat insole having, on its upper surface, under the foot arch or under the waist area, a semi-cylinder arranged perpendicularly to the longitudinal axis and secured on the sole outer surface via a spike connection.

FIG. 8 shows an article of footwear with a training element in the form of a sole segment having a triangular cross-section and narrowing towards the sole inner edge, which is arranged under the foot's outer side, thus causing the lateral border of the foot to be raised in the horizontal plane and causing the foot to be turned inwardly.

FIG. 9 shows an article of footwear with a training element in the form of a sole segment, having a triangular cross-section and gradually narrowing towards the sole outer edge, secured on the sole outer surface via a spike connection, thus causing the medial border of the foot to be raised in the horizontal plane and causing the foot to be turned outwardly.

FIG. 10-11 shows an article of footwear with a training element in the form of a sole forepart segment having a triangular cross-section and gradually narrowing towards the sole central part, secured on the sole outer surface via tongue and groove connections, thus causing the foot toe portion to be raised in the vertical plane.

FIG. 12 shows an article of footwear with a training element in the form of a flat insole having arranged, on its upper surface, in the forepart, a segment having a triangular cross-section and gradually narrowing towards the insole central part, secured on the sole upper surface via a tongue and groove connection or via a mortise and tenon connection as shown in FIG. 13 .

FIG. 14 shows an article of footwear with a training element in the form of an insole having a triangular diagonal section and gradually narrowing in the direction from the outer heel seat region towards the inner forepart region, secured on the sole upper surface via a tongue and groove connection, thus causing the outer region of the foot heel portion to be raised and causing the front inner region of the foot toe portion to gradually descend in the diagonal direction in the vertical plane.

FIG. 15 shows an article of footwear with a training element in the form of an insole having a triangular diagonal section and narrowing in the direction from the inner heel seat region towards the outer forepart region of the sole, secured on the sole upper surface via a tongue and groove connection, thus causing the inner region of the foot heel portion to be raised and causing the front outer region of the foot toe portion to gradually descend in the diagonal direction in the vertical plane.

FIG. 16 shows an article of footwear with a training element in the form of an insole having a triangular diagonal section and narrowing in the direction from the outer forepart region towards the inner heel seat region, secured on the sole upper surface via a tongue and groove connection, thus causing the outer region of the foot toe portion to be raised and causing the inner region of the foot heel portion to gradually descend in the diagonal direction in the vertical plane.

FIG. 17 shows an article of footwear with a training element in the form of a flat insole having a triangular diagonal section and narrowing in the direction from the insole forepart region inner edge towards the heel seat region outer edge, secured on the sole upper surface via a tongue and groove connection, thus causing the inner region of the foot toe portion to be raised in the vertical plane and causing the foot to be turned outwardly.

FIG. 18 shows an article of footwear with a training element in the form of a flat insole having its outer surface gradually sloping from the sole outer edge towards its inner edge, secured on the sole upper surface via a tongue and groove connection, thus causing the foot outer portion to be raised in the horizontal plane and causing the foot to be turned inwardly.

FIG. 19 shows an article of footwear with a training element in the form of a flat insole having its outer surface gradually sloping from its inner edge to its outer edge, secured on the sole upper surface via a tongue and groove connection, thus causing the foot inner portion to be raised in the horizontal plane and causing the foot to be turned outwardly.

FIG. 20 shows an article of footwear with a training element in the form of a part of a flat insole, which is arranged under the heel portion, arch and metatarsus, has a bench under the foot metatarsophalangeal joints, and secured on the sole upper surface.

FIG. 21 shows an article of footwear with a training element in the form of a convex hemisphere arranged in the sole central part, wherein the surface in contact with the foot causes the foot's longitudinal arch to be flexed along the convex surface.

FIG. 22 shows an article of footwear with a training element in the form of a convex hemisphere arranged in the sole central part, wherein the surface in contact with the foot causes the foot's transverse arch to be flexed along the convex surface.

FIGS. 23 a, 23 b show an article of footwear with a training element in the form of an ellipsoid or semi-cylinder arranged between the hallux and the second toe.

FIG. 24 shows an article of footwear with a training element in the form of an elastic insole having an upturned forepart region which straightens under the force exerted by the foot when walking.

FIG. 25 shows an article of footwear with a training element comprised of an insole made from a smooth glossy material and an elastic tricot cover.

FIG. 26 shows embodiments of an article of footwear comprising a training element provided with an elastic layer on its outer surface.

FIG. 27 a-j show embodiments of the elastic layer on the article of footwear outer side.

FIG. 28 shows an article of footwear with a training element, wherein the training element is provided with an additional elastic layers under the toes.

FIG. 29 shows an embodiment of an article of footwear, wherein the means for fastening the article of footwear to the foot is configured in the form of textile straps (slings) secured at the sole edges, and the training element is configured in the form of an insole having holes to secure the straps therein.

FIG. 30 shows an embodiment of an article of footwear, wherein the means for fastening the article of footwear to the foot is configured in the form of textile straps (slings) secured at the sole edges, and the training element is configured in the form of an insole having through cutouts at the insole edge to secure the straps therein.

FIGS. 31 a-h show an article of footwear with a training element in the form of multi-layered insole, comprised by successive layers of various densities: a flat bottom layer having its outer surface secured on the sole upper surface and having secured on its inner surface a hard element in the form of an ellipse or a semi-circle arranged under the foot arch, an intermediate layer formed of an elastic foam material and having a hole for the hard element, and a top flat layer the outer surface of which is in contact with the foot, the layers being bonded to each other via a glue layer.

FIG. 32 shows a set of footwear insoles and inserts for training.

FIG. 33 shows examples of exercises with the use of the article of footwear.

FIG. 34 shows the outcome of exercises according to Example 16.

EXEMPLARY USES OF THE INVENTION Example 1

FIG. 19 shows an article of footwear with a training element in the form of a flat insole having its outer surface gradually sloping from its inner edge to its outer edge, secured on the sole upper surface via a mortise and tenon connection, thus causing the foot inner portion to be raised in the horizontal plane and causing the foot to be turned outwardly. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: posterior tibial muscle (in a smaller         extent), anterior tibial muscle (in a greater extent), long         peroneal muscle.     -   Recommended for: improving general physical fitness, transverse         platypodia preventing and treating; training duration: 15-20         minutes each alternate day.     -   Outcomes: in a girl with platypodia, who worn the article of         footwear for 15 minutes each alternate day during 1.5 months,         the foot arch height increased noticeably, as can be seen from         the ‘before’ and ‘after’ footprints in FIG. 34 ; the legs no         longer got tired when walking; an increase in the overall leg         muscle tonicity was observed.

Example 2

FIG. 18 shows an article of footwear with a training element in the form of a flat insole having its outer surface gradually sloping from the sole outer edge towards its inner edge, secured on the sole upper surface via a mortise and tenon connection, thus causing the foot outer portion to be raised in the horizontal plane and causing the foot to be turned inwardly. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: posterior tibial muscle (in a greater         extent), anterior tibial muscle (in a smaller extent), long         peroneal muscle, short peroneal muscle, third peroneal muscle,         inferior peroneal retinaculum, lateral gastrocnemius head.     -   Recommended for: improving general physical fitness, as an         exerciser for preventing and treating various types of talipes,         training duration: 15-20 minutes per day.

Example 3

Where an article of footwear comprising a combination of two different training elements is used (for training), the training element as shown in FIG. 19 is secured onto the left sole, and the training element as shown in FIG. 18 is secured onto the right sole. In this way, asymmetric training is provided, necessitating the lower limb and back muscle stabilization in order to maintain equilibrium.

-   -   Left foot muscle training: plantar interosseous muscles,         lumbrical muscles, plantar aponeuroses, dorsal interosseous         muscles.     -   Left lower leg muscle training: posterior tibial muscle (in a         smaller extent), anterior tibial muscle (in a greater extent),         long peroneal muscle.     -   Right foot muscle training: plantar interosseous muscles,         lumbrical muscles, plantar aponeuroses, dorsal interosseous         muscles.     -   Right lower leg muscle training: posterior tibial muscle (in a         greater extent), anterior tibial muscle (in a smaller extent),         long peroneal muscle, short peroneal muscle, third peroneal         muscle, inferior peroneal retinaculum, lateral gastrocnemius         head.     -   Recommended for: improving general physical fitness, transverse         platypodia preventing and treating, as an exerciser for         preventing and treating various types of talipes, training         duration: 15-20 minutes per day.

Example 4

Where an article of footwear comprising a combination of two different training elements is used (for training), the training element as shown in FIG. 18 is secured onto the left sole, and the training element as shown in FIG. 19 is secured onto the right sole. In this way, asymmetric training is provided, necessitating the lower limb and back muscle stabilization in order to maintain equilibrium.

-   -   Left foot muscle training: plantar interosseous muscles,         lumbrical muscles, plantar aponeuroses, dorsal interosseous         muscles.     -   Left lower leg muscle training: posterior tibial muscle (in a         greater extent), anterior tibial muscle (in a smaller extent),         long peroneal muscle, short peroneal muscle, third peroneal         muscle, inferior peroneal retinaculum, lateral gastrocnemius         head.     -   Right foot muscle training: plantar interosseous muscles,         lumbrical muscles, plantar aponeuroses, dorsal interosseous         muscles.     -   Right lower leg muscle training: posterior tibial muscle (in a         smaller extent), anterior tibial muscle (in a greater extent),         long peroneal muscle.     -   Recommended for: improving general physical fitness, transverse         platypodia preventing and treating, as an exerciser for         preventing and treating various types of talipes; training         duration: 15-minutes per day.

Example 5

FIG. 9 shows an article of footwear with a training element in the form of a sole segment, having a triangular cross-section and gradually narrowing towards the sole outer edge, secured on the sole outer surface via a spike connection, thus causing the medial border of the foot to be raised in the horizontal plane and causing the foot to be turned outwardly. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: posterior tibial muscle (in a smaller         extent), anterior tibial muscle (in a greater extent), long         peroneal muscle.     -   Recommended for: improving general physical fitness, transverse         platypodia preventing and treating; training duration: 15-20         minutes per day.

Example 6

FIG. 8 shows an article of footwear with a training element in the form of a sole segment having a triangular cross-section and narrowing towards the sole inner edge, which is arranged under the foot's outer side, thus causing the lateral border of the foot to be raised in the horizontal plane and causing the foot to be turned inwardly. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: posterior tibial muscle (in a greater         extent), anterior tibial muscle (in a smaller extent), long         peroneal muscle, short peroneal muscle, third peroneal muscle,         inferior peroneal retinaculum, lateral gastrocnemius head.     -   Recommended for: improving general physical fitness, as an         exerciser for preventing and treating various types of talipes;         training duration: 15-20 minutes per day.

Example 7

FIGS. 10-13 show an article of footwear with a training element in the form of a sole forepart segment having a triangular cross-section and gradually narrowing towards the sole central part, secured on the sole outer surface via tongue and groove connections, thus causing the foot toe portion to be raised in the vertical plane. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles,         extensor digitorum brevis, extensor hallucis brevis, extensor         digitorum longus tendons, extensor hallucis longus tendons.     -   Lower leg muscle training: gastrocnemius muscle.     -   Recommended for: improving general physical fitness,         rehabilitation from extensor digitorum injuries, damaged         peroneal nerve recovery; training duration: 15-20 minutes per         day.     -   Outcomes: a girl working at a beauty shop and having to wear         high-heeled footwear during working hours, who worn the above         article of footwear at home, after work, for 15-20 minutes per         day during 2 months, no longer suffered from leg pain or         swelling at night.

Example 8

FIG. 24 shows an article of footwear with a training element in the form of an elastic insole having an upturned forepart region which straightens under the force exerted by the foot when walking. When walking, the toes press and release the forepart region, acting against the insole resistance. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles,         flexor digiti minimi brevis, flexor digitorum longus tendons,         flexor digitorum brevis tendons, flexor hallucis brevis muscle,         flexor hallucis longus tendon, flexor digitorum brevis, extensor         digitorum brevis, extensor hallucis brevis, extensor digitorum         longus tendons, extensor hallucis longus tendons.     -   Lower leg muscle training: gastrocnemius muscle.     -   Recommended for: as an exerciser for training flexor digitorum         muscles and tendons; training duration: 15-20 minutes per day.

Example 9

FIG. 12 shows an article of footwear with a training element in the form of a sole forepart segment having a triangular cross-section and gradually narrowing towards the sole central part, secured on the sole outer surface via tongue and groove connections, thus causing the foot toe portion to be raised in the vertical plane. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: gastrocnemius muscle, soleus muscle.     -   Recommended for: relaxing and stretching posterior lower leg         muscles in those wearing high-heeled footwear; shortened         Achilles tendon rehabilitation and lower-leg posterior muscle         group training; training duration: 15-20 minutes per day.

Example 10

FIG. 14 shows an article of footwear with a training element in the form of an insole having a triangular diagonal section and gradually narrowing in the direction from the outer heel seat region towards the inner forepart region, secured on the sole upper surface via a tongue and groove connection, thus causing the outer region of the foot heel portion to be raised and providing a gradual descent in the diagonal direction towards the foot anterior inner toe portion in the vertical plane. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: posterior tibial muscle (in a greater         extent), anterior tibial muscle (in a smaller extent), long         peroneal muscle, short peroneal muscle, third peroneal muscle,         inferior peroneal retinaculum, lateral gastrocnemius head.     -   Recommended for: improving general physical fitness, as an         exerciser for preventing and treating various types of talipes;         training duration: 15-20 minutes per day.

Example 11

FIG. 15 shows an article of footwear with a training element in the form of an insole having a triangular diagonal section and narrowing in the direction from the inner heel seat region towards the outer forepart region of the sole, secured on the sole upper surface via a tongue and groove connection, thus causing the inner region of the foot heel portion to be raised and providing a gradual descent in the diagonal direction towards the foot anterior outer toe portion in the vertical plane. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: posterior tibial muscle (in a smaller         extent), anterior tibial muscle (in a greater extent), long         peroneal muscle.     -   Recommended for: improving general physical fitness, transverse         platypodia preventing and treating; training duration: 15-20         minutes per day.

Example 12

FIG. 16 shows an article of footwear with a training element in the form of an insole having a triangular diagonal section and narrowing in the direction from the outer region of the foot toe portion towards the inner region of the foot heel portion, secured on the sole upper surface via a tongue and groove connection, thus causing the outer region of the foot toe portion to be raised and providing a gradual descent in the diagonal direction towards the inner region of the foot heel portion in the vertical plane. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.

Lower leg muscle training: gastrocnemius muscle, soleus muscle, posterior tibial muscle (in a greater extent), anterior tibial muscle (in a smaller extent), long peroneal muscle, short peroneal muscle, third peroneal muscle, inferior peroneal retinaculum, lateral gastrocnemius head.

-   -   Recommended for: improving general physical fitness, as an         exerciser for preventing and treating various types of talipes,         lower-leg posterior muscle group training in high heel wearers.         Training duration: 15-20 minutes per day.

Example 13

FIG. 17 shows an article of footwear with a training element in the form of an insole having a triangular cross-section and gradually narrowing, in the diagonal direction, from the inner surface of the sole forepart region to the outer side of the sole heel seat region, thus causing the inner region of the foot toe portion to be raised in the vertical plane. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: gastrocnemius muscle, soleus muscle,         posterior tibial muscle (in a smaller extent), anterior tibial         muscle (in a greater extent), long peroneal muscle.     -   Recommended for: improving general physical fitness, transverse         platypodia preventing and treating, lower-leg posterior muscle         group training in high heel wearers. Training duration: 15-20         minutes per day.

Example 14

FIG. 20 shows an article of footwear with a training element in the form of an insole having a flat element in the form of a sole segment arranged under the heel portion, arch and metatarsus, creating a height variation

under the foot's metatarsophalangeal joints. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles,         flexor digiti minimi brevis, flexor digitorum longus tendons,         flexor digitorum brevis tendons, flexor hallucis brevis muscle,         flexor hallucis longus tendon, flexor digitorum brevis.     -   Recommended for: as an exerciser for training flexor digitorum         muscles and tendons, rehabilitation from tendon injuries,         rehabilitation from a lower limb neurological disorder; exercise         duration: 15-20 minutes per day.

Example 15

FIG. 7 shows an article of footwear with a training element in the form of a flat insole having, on its upper surface, under the foot arch or under the waist area, a semi-cylinder arranged perpendicularly to the longitudinal axis and secured on the sole outer surface via a spike connection. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles.     -   Lower leg muscle training: all lower leg muscles, except for the         soleus and gastrocnemius muscles.     -   Recommended for: as an exerciser for longitudinal platypodia         preventing and treating; training duration: 15-20 minutes each         alternate day.     -   Outcomes: in a girl with platypodia, who worn the article of         footwear for 15 minutes each alternate day during 1.5 months,         the foot arch height increased noticeably, as can be seen in         FIG. 33 from the ‘before’ and ‘after’ footprints; the legs no         longer got tired when walking; an increase in the overall leg         muscle tonicity was observed.

Example 16

FIGS. 3, 5, 6 show an article of footwear with a training element in the form of a semi-cylinder (or an insole with a semi-cylinder) arranged on the sole upper surface in contact with the foot along the sole longitudinal axis. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles,         adductor hallucis muscle.     -   Lower leg muscle training: all peroneal muscles and the anterior         tibial muscle, lateral stabilizers of the ankle joint.     -   Recommended for: strengthening the foot deltoid and peroneal         ligaments, transverse platypodia preventing and treating (in a         greater extent), longitudinal platypodia preventing and treating         (in a smaller extent); exercise duration: 15-20 minutes each         alternate day.     -   Outcomes: in a girl with platypodia, who worn the article of         footwear for 15 minutes each alternate day during 1.5 months,         the foot arch height increased noticeably, as can be seen in         FIG. 34 from the ‘before’ and ‘after’ footprints, the legs no         longer got tired when walking, an increase in the overall leg         muscle tonicity was observed.

Example 17

FIG. 21 shows an article of footwear with a training element in the form of a convex hemisphere arranged in the sole central part, wherein the surface in contact with the foot causes the foot's transverse arch to be flexed along the convex surface. By using such article of footwear, the following muscles are trained.

-   -   Lower leg muscle training: gastrocnemius muscle, soleus muscle.     -   Recommended for: rehabilitation from forefoot or hindfoot         injuries, bearing on the midfoot; exercise duration: 15-20         minutes.

Example 18

FIG. 22 shows an article of footwear with a training element in the form of a convex hemisphere arranged in the sole central part, wherein the surface in contact with the foot causes the foot's longitudinal arch to be flexed along the convex surface. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles,         adductor hallucis muscle.     -   Lower leg muscle training: all peroneal muscles and the anterior         tibial muscle, lateral stabilizers of the ankle joint.     -   Recommended for: improving general physical fitness, relaxation         in the evenings. Transverse platypodia preventing and treating;         longitudinal platypodia preventing and treating; exercise         duration: 15-20 minutes.

Example 19

FIG. 23 shows an article of footwear with a training element in the form of an ellipsoid or semi-cylinder arranged between the hallux and the second toe. The training elements are exchangeable and are of different sizes. By using such article of footwear, the following muscles are trained.

-   -   Foot muscle training: plantar interosseous muscles, lumbrical         muscles, plantar aponeuroses, dorsal interosseous muscles,         adductor hallucis muscle.     -   Recommended for: non-operative treatment of Hallux valgus or         rehabilitation from a Hallux valgus surgery; exercise duration:         15-20 minutes.

Example 20

FIG. 4 shows an article of footwear with a training element in the form of a flat insole following the shape of the sole, of different thicknesses for the left foot and for the right foot. By using such article of footwear, the following muscles are trained.

-   -   Muscle training: deep muscles of the pelvis, gluteal muscles,         knee joint muscles.     -   Recommended for: improving general physical fitness with the         load focused primarily on the thighs; relaxing within a limited         time period of 10-15 minutes and obligatory alteration of         asymmetry. As a corrective footwear for those with lower limb         asymmetry.     -   Outcome: in a customer, who worn the article of footwear during         1 month as part of rehabilitation from and training after a         thigh injury for 10-15 minutes per day with alteration of         asymmetry within a single training session, a noticeable         reduction of pain and increased tonicity of the leg and gluteal         muscles were observed.

Example 21

FIG. 25 shows an article of footwear wherein the training element is configured in the form of an insole having a smooth sliding surface, for example, made from paper with an adhesive layer for gluing to the sole, and an additional elastic cover, so as to provide for maximum sliding of the cover over a smooth surface.

-   -   Muscle training: all lower limb (foot, lower leg, thigh, pelvis)         muscles, back muscles.     -   Recommended for: improving general physical fitness without any         wearing time limitation. Due to the unstable position of the         foot on the support, the lower limb and back muscles have to be         stabilized in order to maintain equilibrium. 

1. An article of footwear for strengthening foot and lower leg muscles and for developing overall body coordination, comprising a means for fastening the article of footwear to the wearer's foot, a flat sole, the underside of which is in contact with flooring, and the upper surface of which is constructed with a training element for interacting with the wearer's foot, characterized in that the training element is designed to be exchangeable for changing the type of training and is secured within the sole upper layer via a spike connection, or snap fasteners, or an adhesive layer, or a textile fastener. 2-5. (canceled)
 6. The article of footwear of claim 1, wherein it is designed for wearing on either right or left foot. 7-8. (canceled)
 9. The article of footwear of claim 1, wherein the training element is configured in the form of a flat insole with a thickness of 5 to 60 mm.
 10. The article of footwear of claim 1, wherein the training element is configured in the form of a flat insole having a smooth outer surface providing for the foot sliding over a smooth surface.
 11. The article of footwear of claim 10, wherein the training element further includes an elastic tricot cover providing for the foot sliding over a smooth surface.
 12. The article of footwear of claim 1, wherein the training element is configured in the form of a semi-cylinder or a polyhedron having its base secured on the sole upper surface along the longitudinal axis of the latter. 13-19. (canceled)
 20. The article of footwear of claim 1, wherein the training element is configured in the form of a flat insole having arranged, on its upper surface, in the forepart, a segment having a triangular cross-section and gradually narrowing towards the insole central part, thus causing the foot toe portion to be raised in the vertical plane. 21-27. (canceled)
 28. The article of footwear of claim 1, wherein the training element is configured in the form of a convex hemisphere arranged in the sole central part, wherein the surface in contact with the foot causes the foot's transverse arch to be flexed along the convex surface. 29-31. (canceled)
 32. The article of footwear of claim 1, wherein the training element is configured in the form of an elastic insole having an upturned forepart region configured to straighten under the force exerted by the foot when walking. 33-34. (canceled)
 35. An article of footwear for strengthening foot and lower leg muscles and for developing overall body coordination, comprising a means for fastening the article of footwear to the wearer's foot, a flat sole, the underside of which is in contact with flooring, and the upper surface of which is constructed with a training element for interacting with the wearer's foot, characterized in that the means for fastening the article of footwear to the foot is configured in the form of elastic slings secured at the edges of the sole, and the training element in the form of an insole has through cutouts through which the slings can be passed and is designed to be exchangeable. 36-42. (canceled)
 43. The article of footwear of claim 35, wherein the training element is provided with a semi-cylinder or polyhedron secured on its upper surface, under the foot arch or under the waist area, perpendicularly to the longitudinal axis.
 44. (canceled)
 45. The article of footwear of claim 35, wherein the training element has a triangular diagonal section and gradually narrows in the direction from the outer heel seat region towards the inner forepart region, thus causing the outer region of the foot heel portion to be raised and causing the front inner region of the foot toe portion to gradually descend in the diagonal direction in the vertical plane.
 46. The article of footwear of claim 35, wherein the training element has a triangular diagonal section and narrows in the direction from the inner heel seat region towards the outer forepart region of the sole, thus causing the inner region of the foot heel portion to be raised and causing the front outer region of the foot toe portion to gradually descend in the diagonal direction in the vertical plane.
 47. The article of footwear of claim 35, wherein the training element has a triangular diagonal section and narrows in the direction from the outer region of the foot toe portion towards the inner region of the foot heel portion, thus causing the outer region of the foot toe portion to be raised and causing the inner region of the foot heel portion to gradually descend in the diagonal direction in the vertical plane.
 48. The article of footwear of claim 35, wherein the training element has a triangular diagonal section and narrows in the direction from the inner forepart region towards the outer heel seat region, thus causing the inner region of the foot toe portion to be raised in the vertical plane and causing the foot to be turned outwardly.
 49. The article of footwear of claim 35, wherein the training element has its outer surface gradually sloping from the insole outer edge towards its inner edge, thus causing the foot outer portion to be raised in the horizontal plane and causing the foot to be turned inwardly.
 50. The article of footwear of claim 35, wherein the training element has its outer surface gradually sloping from its inner edge to its outer edge, thus causing the foot inner portion to be raised in the horizontal plane and causing the foot to be turned outwardly.
 51. The article of footwear of claim 35, wherein the training element is provided with flat thickened portion arranged under the heel portion, arch and metatarsus so as to form a bench under the foot's metatarsophalangeal joints. 52-53. (canceled)
 54. The article of footwear of claim 35, wherein the training element includes an ellipsoid or a semi-cylinder secured between the hallux and the second toe. 55-56. (canceled)
 57. A training kit, characterized in that it includes the article of footwear of claim 1 and at least two training elements configured to be exchangeable for changing the type of training. 